Macular Degeneration: Implantable Telescope Improves Vision
ATLANTA (Ivanhoe Newswire) - Macular degeneration is the leading cause of severe vision loss in Americans 60 and older. Once it progresses there aren't many treatment options, but now there is a high-tech way that doctors are using to help patients see better.
Macular degeneration stole Jackie Carswell's central vision.
"I couldn't read a recipe. I couldn't work a microwave. I couldn't hardly do anything. I asked the doctor one day if there was anything else that can be done for this," Jackie Carswell told Ivanhoe.
Doctors suggested she try this miniature telescope.
"It contains lenses, or optics, that make an image magnified," Susan A. Primo, OD, MPH, Director of Vision and Optical Services at Emory Eye Center, told Ivanhoe.
Surgeons removed Jackie's natural lens and replaced it with the tiny implant that enlarges objects.
"It's a three-times telescope, which means, theoretically, it improves vision by almost three-times," Dr. Primo said.
The telescope is only implanted in one eye.
"Now, these folks are bi-ocular. The use one eye for one thing and one eye for the other," Dr. Primo explained.
It takes about twelve weeks of training and rehab for patients to master the new device. In one study, nine out of ten patients with the telescopic implant improved vision by at least two lines on the eye chart.
The telescopic implant is helping Jackie keep a lot of her independence.
"I was determined that I'd make it, and that I'd do it. Now, I have and I am!" Jackie said.
The telescope implant is FDA approved for patients 75 and older who have advanced wet or dry macular degeneration. The most common risks include inflammatory deposits on the device and increased pressure in the eye.
BACKGROUND: Age-related macular degeneration (AMD) is a common condition and the leading cause of vision loss in people who are 50 and older. It slowly destroys the part of the eye that allows sharp, central vision needed for seeing objects clearly, known as the macula. AMD can advance so slowly in some that vision loss does not occur for a long time. In others, the disorder can progress faster and can lead to a loss of vision in one or both eyes. The vision loss associated with AMD makes it difficult to recognize faces, drive a car, read, and write. The macula is made up of millions of light-sensing cells that allow for sharp, detailed central vision. It's the most sensitive part of the retina. The retina quickly turns light into electrical signals and then sends the electrical signals to the brain through the optic nerve. The brain then translates the electrical signals into images. When the macula is damaged, fine points in the images become unclear. (Source: www.nei.nih.gov)
STAGES: There are two forms of AMD: dry and wet. Both forms can advance and cause severe vision loss. The dry form is more common and it occurs in about 90 percent of the people with the condition. It also has three stages: early, intermediate, and advanced. It occurs when the light-sensitive cells in the macula slowly break down, gradually blurring central vision. The wet form is considered advanced AMD and can be more severe. It happens when new blood vessels under the macula leak fluid and blood. All people who have the wet form had the dry form first. (Source: www.nei.nih.gov)
NEW TECHNOLOGY: There is no cure for End-Stage AMD. It is uncorrectable by drugs, glasses, or cataract surgery. However, the CentraSight treatment program can help improve vision. The telescope implant has been shown to improve vision and quality of life in appropriate patients with End-Stage AMD. The program uses a tiny telescope, created from VisionCare Ophthalmic Technologies. The implantable telescope is about the size of a pea. It is implanted behind the iris, the colored part of the eye. The implant is barely noticeable in the eye. Once the telescope is implanted inside the eye, it projects images in the field of view onto healthy areas of the central retina outside of the degenerated macula. The image is enlarged and it reduces the effect the blind spot has on the central vision. Usually the healthy areas outside the macula are used for peripheral vision. The magnification the telescope implant provides (2.2x or 2.7x) makes it possible to see or discern the central vision object of interest. In the CentraSight treatment program, a person uses the eye with the telescope implant for detailed central vision (like reading). The other eye is used for peripheral vision (like checking for cars while driving). The implant doesn't limit the natural eye movements and it doesn't require the patient to move their entire head, unlike external magnifying appliances. As a patient in the CentraSight program, they will need to work with low vision specialist to develop the skills they need to use. One of the skills that they have to learn is how to switch their viewing back and forth between the eye with the telescope implant and the eye without the implant. They will also need to wear eye glasses and may need to sometimes use a hand-held magnifier with the telescope-implanted eye to read. (Source: http://www.centrasight.com)
Susan A. Primo, OD, MPH, Director of Low-Vision Services and Optometry at Emory Eye Center, talks about a new treatment for macular degeneration.
How many people do you treat with macular degeneration?
Dr. Primo: I would say probably hundreds of patients. Age-related macular degeneration (AMD) is the most common eye condition contributing to loss of vision.
What happens to these people?
Dr. Primo: There are mild forms of AMD and there are more severe forms. We see patients on either end of the spectrum. So, I work with people who are moderately to severely visually impaired. Some people who have early stages of macular degeneration do fine in the sense that their vision is not profoundly affected, but those that have more advanced disease where their vision gets really poor is where I come in.
What happens to their vision?
Dr. Primo: Basically they have decreased central vision so the peripheral vision or the side vision remains intact. As a result, visual acuity drops and so does their ability to function and do some activities of daily living. Many feel like it robs them of their independence.
That is where I come in by utilizing vision rehabilitation, low vision devices or tools, techniques, and strategies to help people to regain and maintain independence. That is the goal of what I do.
Is there nothing to cure it with?
Dr. Primo: There is no cure. There are certainly treatments that are out there that may lessen the severity of some forms of macular degeneration, but there is no cure. That is correct.
Can you reverse it at all?
Dr. Primo: No. There is a wet form or a bleeding form of AMD that can occur and retinal specialists use injections inside the eye; these Anti-VEGF treatments can reduce some of that bleeding. There are also laser techniques, but AMD is not reversible in that sense. The injections certainly can minimize the effects of some of the bleeding forms.
Now there is a new mini-telescope that you can implant. Can you explain that?
Dr. Primo: It is called the implantable miniature telescope (IMT). We participated in the phase 3 clinical trial here at Emory. In 2003-2004, we had about 17 patients implanted here. There were over 200 patients implanted across the country during the trial. There was also a clinical trial in the UK in 2008. So, with the FDA approval of the IMT in July, 2010, we are actually starting to implant patients here in this country. Three have been done here at Emory so far and perhaps 50 or so across the country. However, not every person that has AMD is a candidate for this telescope prosthesis. There are certain characteristics with their vision and with their personality that make some people better candidates. We learned a lot about what makes a good candidate from the clinical trials.
Can you give me examples of a good candidate?
Dr. Primo: This person has to be very upbeat and very motivated, likely not a Type-A individual that wants perfection, because this is not a cure or a magic bullet! It needs to be someone who has very specific goals, whether it's reading, watching television, or seeing their grandkids; again, someone who has very specific goals and is willing to accept some of the challenges that come with the device. So, about 1 in 5 patients that I see will end up being a good candidate.
Does it work for both wet and dry?
Dr. Primo: It is for end-stage AMD, whether it is the wet form or dry form, meaning that no further medical treatment is required.
So, what is this telescope?
Dr. Primo: Well, it is a tiny telescope prosthesis measuring about 3.5 mm in diameter and about 4.5 mm in length, which means it is very small compared to anything else you might have seen (an inch is 25 mm), but is larger than the typical intraocular lens used in traditional cataract surgery. Due to its size, it requires a very specific surgical technique. It is not a standard cataract extraction. It is a lot more complicated than that. The device contains lenses or optics that creates a magnified or larger image. Now, if you have ever used a binocular or telescope before, you know that while you get this nice magnified image, you also get a reduction in your side vision, kind of like tunnel vision. Therefore, the device is only implanted in one eye because a person uses the other eye to maintain their peripheral vision, their ability to walk, and other gross activities like that. They use alternate eye viewing where the telescopic eye is essentially shut off for walking, etc. and the fellow eye is shut off so the telescopic eye can do more detailed work like reading, seeing people's faces and watching television. So, you can see that it requires some significant training. It is not just this telescope that is implanted and then we say good-bye to the patient. We spend several weeks and months rehabilitating the patient to be able to conquer this alternate eye viewing technique.
So, it is an extreme case of training, kind of like bifocals?
Dr. Primo: It is similar in the sense that you are learning to use your vision in a different way than you did before.
Do you have to rewire your brain?
Dr. Primo: Basically, the brain does get rewired or re-programmed to be able to know when to shut each eye off. We call it bi-ocular viewing status instead of binocular, where you are using two eyes together.
What is the training in that?
Dr. Primo: The training is pretty extensive. It is important to understand that with having the IMT procedure, a true vision rehabilitative team approach is necessary. It's not just the surgeon implanting the device. It is also the occupational therapist (OT) who spends several weeks, almost months training the patient to use alternate eye viewing skills to be able to know when to "turn an eye off" and when to "turn it on"; and the low vision optometrist helping to oversee and guide the process. Most patients will require extensive training, for at least 12 weeks after the implantation.
Does it give their vision back? Would it look the same or are you just seeing shadows?
Dr. Primo: No. The device is a 3X telescope, which means theoretically it improves the vision by almost three times. If a person started out at 20/200, he/she is going to get three times better vision than that, something like 20/70. So, no one really gets to 20/20 again of course, but people can get to somewhere around 20/100, maybe a little bit worse than that depending upon what the initial visual acuity was. For someone who's legally blind, a three times increase in their vision allows them to perform activities of daily living skills better, see facial expressions and perhaps to read small print again.
Can you explain the surgery?
Dr. Primo: While I'm not the surgeon, I do know that it requires a fairly large incision of about a 10 or 12 mm. This is why we have a cornea or anterior segment surgeon perform the surgery. It is similar to cataract surgery in the sense that the natural lens is removed and this prosthesis is put in, but it is different than traditional cataract surgery because this device is much larger, and also, as I said, it requires a lot more manipulation of the eye.
Tell me about Jackie. What was she like when you first met her?
Dr. Primo: She is just fantastic. I knew that she was going to be a good candidate because of her personality type. She lives alone in a rural area and wants to obviously remain as independent as possible. She is willing to go the extra mile to be able to make this successful and that is really what takes is. Her visual acuity met the guidelines for what the FDA says the vision has to be; so from that standpoint, she was fine.
Did you help train her with her eyes?
Dr. Primo: I did. We did a pre-implantation evaluation and training to determine if she was a good candidate. Our OT spent some time making sure that she could handle some of the concepts. The surgery happened and then she spent about 12 weeks or so post implantation in occupational therapy, where my OT and I went back and forth with some techniques we had to use to be able to get her to progress. However, each patient progresses at a different rate.
How often did she have to come in?
Dr. Primo: She had to come in weekly for several weeks.
Is this the most hopeful thing that has happened?
Dr. Primo: Well, I think it is the only thing that we have at this point, aside from traditional vision rehabilitation, which is often very successful, where we were use tools like magnifiers and external and electronic devices. So, I think this now gives people the advantage from an aesthetic standpoint. You would hardly be able to tell if someone has one of these implanted. From that standpoint, I think that people are able to utilize it well to get this three times improvement in vision, other than some form of optical device; there is really nothing else that we have for end-stage AMD.
Are there any age requirements?
Dr. Primo: 75 years of age or older is what the device is labeled for, but it clearly depends on the individual. The IMT could certainly go in a 95-year-old, if that person were still active and able to understand the concepts that we are trying to train them on.
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